[Flathead Fever]

I had to think about this for a minute. Its not something I use very often anymore.

I'm no sure how running a ballast resistor in series with an internal resister coil would burn out a ballast resister? You obviously do not want to do that because the available voltage would be too low for the coil to properly operate.

I check some sources that quoted the following resistance readings. A Chrylser ballast resister is 1.4 ohms with an additional 1.5 ohms of resistance in the primary coil windings. An internal resister coil has 3.0 ohm's of resistance. I have no idea how accurate those specifications are but I'm going to use them for reference.

Using Ohm's law 12.6V divided by 1.4 Ohms, would create a circuit with 9 amps. That is too much current for the tiny wire used in the primary winding in the coil and it would eventually burn that wire up. But in our equation we did not take into account we still have an additional 1.5 ohms of resistance in that tiny primary winding. You add the two resistances together, 12.6V divided by 2.9 ohms. That creates a circuit with 4.34 amps. Every thing on that circuit has 4.34 amps running through it. 4.34 amps would be flowing through the ballast resister and the coil primary winding. Adding resistance lowers the amperage flow which is less heat on the ballast resistor and primary coil winding.

If you used a ballast resister (1.4 ohms) along with an internal resister coil (3 ohms) that would drop the overall amperage even further. 12.6V divided by 4.4 ohms would give you 2.86 amps flowing through the circuit. The coil will not perform as it should. but the lower amperage would put less of a load on the ballast resister. I don't see how that would be the problem. If there was not enough resistance in the primary coil windings we would be at that previous 9 amp calculation, that would cause the ballast resistor it to overheat and fail.

The only other thing I can think of is faulty ballast resistors. By brand name parts. I was a fleet mechanic. I at one time we had at hundreds of Chrysler vehicles in the yard. Almost all with ballast resistors. I immediately new the problem was when they burned out. They would crank and start but then immediately quit when you stopped cranking. That's because when its cranking it is bypassing the ballast resistor for a hotter spark as soon as you release the key your back to running on the ballast resister. We used "Standard" brand replacement resistors with out any problems but that was 30-year's ago.